La Jolla geologist and photographer John Shelton dies, July 24

Shelton currently has an exhibit of his photographs on display at the San Diego Natural History Museum. It will run through Nov. 2.

Shelton graduated from La Jolla High in 1931 and went on to Pomona College.

"I didn't discover geology until my junior year," Shelton said in a recent interview with the La Jolla Light. Too far along in his studies to change majors, he graduated with a dual degree in math and music.

He returned to Francis Parker but could not escape enthrallment with the earth's history.

"It's fascinating to speculate on where we all came from and where we're all going," Shelton said.

He turned to the college professor who had introduced him to geology, and upon his advice, applied to Yale.

"I feel like my whole life has been a procession of (overlapping) interests," he said in the interview with the Light.

Shelton resumed teaching and worked for the U.S. Geological Survey. An avid pilot, he logged almost 6,000 hours over his lifetime.

Always on the lookout for a new way to reach his students, Shelton began taking photographs of different land formations to demonstrate the dynamic geologic forces at work. His collection of photos, begun in the '30s and continuing through the '90s, spans the globe, including Scandinavia, Europe and the U.S.

Critical of textbooks and curriculums that teach geology through memorization, he authored "Geology Illustrated," which was later named one of the most important 100 books of the last 100 years by Scientific American.

Shelton called himself a "student of the earth."

The current Natural History Museum show, "Aerial Portraits of the American West," offers a unique perspective of geologic formations and processes from Alaska to Baja California. The photographs were taken by Shelton over the course of several decades.

"It's a collection of four by five (inch) negatives that John shot from the 1940s right up through the '70s," said Michael Field, the exhibit designer.

Shot with a military aerial reconnaissance camera, the negatives are so large that they show tremendous detail. Many of the photos would be nearly impossible to capture today because air clarity has been reduced by pollution.

"I'm one of his fans," Field said. "When I took geology in college back in the day, I remember looking at his pictures and having an 'aha' moment."

Recognized as one of the most influential geologists in the country, Shelton's photographs provided evidence of principles such as continental drift and plate tectonics. One of his most well known photos showcases an orange grove that straddled the San Andreas fault and was misaligned during an earthquake.

"It clearly illustrated the land we live on is … moving north," Field said. "It provided this evidence or body of work for people to better understand the concept of the earth in motion, this elastic crust we live on."